"Barbie" was a big hit at the box office and at costume parties ... celebs dressing up as the iconic doll (and movie character) include Kelsea Ballerini and YouTuber Sierra Furtado ... and we just can't get Kenough.

Drew Barrymore went old school with an ode to Bob Ross ... complete with a hairy chest, afro and a goatee. Get Drew an easel, some paint and a fresh canvas, STAT!!!

The most timely duo costume was definitely Taylor Swift and Travis Kelce, and we saw versions from 2 IRL couples -- Kelly Ripa and Mark Consuelos and Rachel Zoe and hubby Rodger Berman.

The Casamigos party was littered with celebs who went all out with their costumes. Most of 'em hit home runs, but Heidi Klum just might take the cake here.

As is her tradition ... Heidi got super creative and intricate with her Halloween costume -- a flowing pink cape, tons of makeup, facial prosthetics and a very spooky vibe. Ya gotta imagine it took hours to finish, so props to HK for pulling off another unique look.

Go easy on the candy, and we'll see ya next year for more Hollywood sights and frights!!!